Please forgive me if I over-explain and you're a physician as I'm not sure if curious MD stands for medical doctor or muscular dystrophy.
It would be very, very unlikely (if not impossible) that there would be 3 different kinds of dystrophies in one family. In fact, I don't even think that anyone would ever believe it even if it was true. The problem is that the diagnoses were probably made on clinical grounds alone which just isn't that reliable given the advanced testing that's available today. For more definitive testing, genetics testing will need to be done on one of the family members, if not all affected for confirmation. As for the statement about not having any dystrophy due to the fact that "physical aptitude is normal", that isn't true. We have seen a number of patients who feel fine and function normally but turn out to have subtle weakness on exam and some kind of limb-girdle dystrophy on genetics testing. Some may even be completely normal with positive genetics testing. My guess is that this family probably has some kind of limb-girdle dystrophy (the same one) that is likely autosomal dominantly inherited (meaning that one of the parents had a dominant allele that has 50% chance of being passed on to each child) with incomplete expression in that parent. But that's just a guess. As for your wife, hard to say as we're not sure what this is yet. But if it does turn out ot be autosomal dominant inheritance, she has a 50% chance of having the disease and so will each child that you have. If she doesn't have it, then your kids wil be scott free, too, assuming you don't have the disease. Good luck.